1. Field of the Invention
This invention relates to clean room systems and, in particular, clean room ceiling systems. "Ceiling" herein includes not only horizontal upper walls and lower walls or floors of rooms but also vertical side walls. The terms lower, upper, above, below, and the like and their cognitives have reference to a conventional ceiling installation and are to be understood as relative terms when the "ceiling" is other than above the workspace. The invention further relates to filter units comprising a frame and filter media sealed in the frame, support structure comprising a support such as a grid or other array of support elements, or a filter unit receiver of one or more interconnected modular bays congruent and close-fitting with the filter units, and plural spring-loaded latch and keeper fasteners for separably attaching the filter units into the support structure with a simple push-in, pull-out movement.
2. Related Art
Clean room ceilings are known and typically comprise one or more filter units supported by a structure that is separate or integral with the filter units. Facile installation and removal of the filter units, which are replaced from time-to-time, is of increasing importance. Replacement from the room side of the filter system is desirable for increased convenience and lower cost. The need to air-tightly mount the filter units in their filter support structure has lead to the use of supports that have flanges or lips against which the filter units rest in sealed condition. Passing the flanges to insert filter units can be problematic. More recently, it has been demonstrated that sealing tape can be used at the interstices of the filter arrays to block unfiltered air flow, eliminating in some systems the use of support flanges, and easing the insertion problem.
In clean room systems that use one or a plurality of single filter units each in its own enclosing frame so that there is no large plenum over a number of filters as in grid systems, the testing of the filters for integrity involves the addition of a test material (an aerosol typically) to the air stream entering the filter. In a further aspect the present invention provides a novel and highly convenient way to accomplish this test. In addition, the filter units of the invention further permit adjustment of incoming air flow by selective positioning of a damper from the room side of the filter unit.